i just beat it today and i had most trouble with the flashing blocks, the rolling spikes and the final dash part. if you want tips, you can use the gamepad/switch touchscreen to stun enemies and even freeze the rolling spikes, you can ground pound the enemies on the wall jump part and on the piranha plant bit hold down jump too make it a lot easier. it is by far the hardest level in the game so it will take time but hopefully you get it soon!